Type D hepatitis, the most severe form of viral hepatitis, is caused by infection with hepatitis D (delta) virus (HDV), a sub-viral satellite of hepatitis B virus (HBV) (Smedile, A., et al. (1994) Prog Liver Dis 12, 157-75). Compared with other agents of viral hepatitis, acute HDV infection is more often associated with fulminant hepatitis, a rapidly progressive, often fatal form of the disease in which massive amounts of the liver are destroyed. Chronic type D hepatitis is typically characterized by necroinflammatory lesions, similar to chronic HBV infection, but is more severe, and frequently progresses rapidly to cirrhosis and liver failure, accounting for the disproportionate association of chronic HDV infection with terminal liver disease (Smedile, A., et al. (1994) Prog Liver Dis 12, 157-75; Rizzetto, M., et al. (1983) Ann Intern Med 98, 437-41). Although HDV infection affects fewer individuals than HBV alone, the resulting acute or chronic liver failure is a common indication for liver transplantation in Europe as well as North America (Smedile, A. & Rizzetto, M. (1992) Int J Clin Lab Res 22, 211-215; Wright, T. L. & Pereira, B. (1995) Liver Transplant Surgery 1, 30-42). Chronic disease affects 15 million persons worldwide, about 70,000 of whom are in the U.S. The Centers for Disease Control estimates 1,000 deaths annually in the U.S. due to HDV infection (Alter, M. J. & Hadler, S. C. (1993) Prog Clin Biol Res 382, 243-50; Alter, M. J. & Mast, E. E. (1994) Gastroenterol Clin North Am 23, 437-55).
There is currently no generally accepted effective therapy for type D hepatitis, and liver transplantation is the only option for the associated end-stage liver disease. Although interferon alpha has been moderately successful in treating some cases of type D hepatitis, the need for better treatment options is indicated by the very high doses required, variable responses, frequent relapse after cessation of treatment, and difficulties in drug administration (Thomas, H. C. et al. (1987) Prog Clin Biol Res 234, 277-90; Hoofnagle, J. et al. (1987) Prog Clin Biol Res 234, 291-8; Rosina, F. et al. (1987) Prog Clin Biol Res 234, 299-303; Rosina, F. et al. (1991) Hepatology 13, 1052-6; Farci, P. et al. (1994) N Engl J Med 330, 88-94; Hadziyannis, S. J. (1991) J Hepatol 13 Suppl 1:S21-6; Di Marco, V. et al. (1996) J Viral Hepat 3, 123-8; Porres, J. C. et al. (1989) J Hepatol 9, 338-44).
Lamivudine (β-L-2′,3′-dideoxy-3′-thiacytidine, 3TC) is a synthetic nucleoside shown to be effective in treating HIV and HBV infection. See U.S. Pat. No. 5,539,116 to Liotta et al. Lamivudine is known to cause sustained suppression of HBV replication during treatment (Nevens, F. et al. (1997) Gastroenterology 113:1258-1263). However, lamivudine does not improve disease activity or lower HDV-RNA levels in patients with chronic delta hepatitis (Lau, D. T. et al. (1999) Hepatology 30, 546-9). Lamivudine was recently approved in the U.S. and several other countries for treatment of chronic HBV infection. Prolonged treatment of chronic HBV carriers with lamivudine leads to decreased levels of HBV in serum and improved liver histology (Lai, C. L. et al. (1998) N Engl J Med 339, 61-8; Tyrrell, D. et al. (1993) Hepatology 18, 112A; Nevens, F. et al. (1997) Gastroenterology 113, 1258-63; Dienstag, J. L. et al. (1995) N Engl J Med 333, 1657-61). Despite the dramatic effects on HBV, lamivudine treatment of patients chronically infected with both HBV and HDV has little effect on circulating levels of HDV; more importantly, there is no improvement in disease activity even though HBV levels are suppressed (Honkoop, P. et al. (1997) Hepatology 24 (Suppl), 1219 (Abstract); Lau, D. T. et al. (1999) Hepatology 30, 546-9).
Additional forms of treatment have been tried. For example, suramin in vitro blocks the entry of the virion into hepatocytes, but it is too toxic to be acceptable for long term use in humans (Smedile, A., et al. (1994) Prog Liver Dis 12, 157-75). Acyclovir enhances HDV replication in vitro (Smedile, A., et al. (1994) Prog Liver Dis 12, 157-75). Ribavirin did not significantly affect virological or biochemical parameters and had severe side-effects (Smedile, A., et al. (1994) Prog Liver Dis 12, 157-75). Synthetic analogs of thymosin have also been ineffective in the treatment of HDV infection (Smedile, A. et al. (1994) Prog Liver Dis 12, 157-75).
None of the described treatments for HDV infection are generally accepted as effective. The HDV virion is composed of a ribonucleoprotein core and an envelope. The core contains HDV-RNA, and hepatitis delta antigen (HDAg), which is the only protein encoded by this virus (Wang, K. S. et al. (1986) Nature 323, 508-14). The envelope is formed by the surface antigen protein (hepatitis B surface antigen, or HBsAg) of the helper virus, hepatitis B. (Bonino, F. (1984) Infect Immun 43, 1000-5; Bonino, F. et al. (1981) Hepatology 1, 127-31; Bonino, F. et al. (1986) J Virol 58, 945-50). The envelope is the sole helper function provided by HBV. HDV is able to replicate its RNA within cells in the absence of HBV (Kuo, M. Y. et al. (1989) J Virol 63, 1945-50), but requires HBsAg for packaging and release of HDV virions (Wu, J. C. et al. (1991) J Virol 65, 1099-104; Ryu, W. S. et al. (1992) J Virol 66, 2310-2315.), as well as for infectivity (Sureau, C., et al. (1992) J Virol 66, 1241-5). As a result of the dependence of HDV on HBV, HDV infects individuals only in association with HBV.
Because the woodchuck hepatitis virus (WHV) is closely related to HBV (ca. 85% nucleic acid homology), it has been widely used as a model for HBV infection and disease in its natural host, the eastern woodchuck (M. monax) (Gerin, J. L. (1990) Gastroenterol Jpn 25 (Supp), 38-42; Tennant, B. C. et al. (1988) Viral Hepatitis and Liver Disease, 462-464). Experimentally infected woodchucks have also been used extensively for analysis and development of anti-HBV therapeutics. (Zahm, F. E. et al. (1998) Ital J Gastroenterol Hepatol 30, 510-6; Tennant, B. C. et al. (1998) Hepatology 28, 179-91; Mason, W. S. et al. (1998) Virology 245, 18-32; Korba, B. E. et al. (1996) Hepatology 23, 958-63; Hurwitz, S. et al. (1998) Antimicrob Agents Chemother 42, 2804-2809; Block, T. M. et al. (1998) Nat Med 4, 610-4; Cullen, J. M. et al. (1997) Antimicrob Agents Chemother 41, 2076-82; Fourel, G. et al. (1990) Nature 347, 294-8; Gangemi, J. et al. (1997) Antivir Therap 1, 64-70; Genovesi, E. V. et al. (1998) Antimicrob Agents Chemother 42, 3209-17; Korba, B. E. et al. (2000) Antiviral Res 45, 19-32; Korba, B. E. et al. (2000) Antiviral Therapy 55, 95-105; Korba, B. E. et al. (2000) Antimicrobial Agents and Chemotherapy 44, 19-32. The efficacy of several anti-HBV agents used to experimentally treat chronic WHV infection in woodchucks (araAMP, ribavirin, AZT, ACV, 3TC, famciclovir, FTC, alpha-interferon, fialuridine ganciclovir, thymosin alpha-1, combination therapy with 3TC and alpha-interferon or 3TC and famciclovir) has accurately paralleled the efficacy and toxicity profiles of these agents administered to HBV patients treated in the course of clinical trials. The similar efficacy observed in WHV infected woodchucks and HBV infected persons treated with anti-HBV agents demonstrates that the woodchuck animal model can be predictive for anti-HBV therapies in man (Zahm, F. E. et al. (1998) Ital J Gastroenterol Hepatol 30, 510-6; Tennant, B. C. et al. (1998) Hepatology 28, 179-91; Mason, W. S. et al. (1998) Virology 245, 18-32; Hurwitz, S. et al. (1998) Antimicrob Agents Chemother 42, 2804-09; Fourel, G. et al. (1990) Nature 347, 294-8; Gangemi, J. et al. (1997) Antivir Therap 1, 64-70; Genovesi, E. V. et al. (1998) Antimicrob Agents Chemother 42, 3209-17; Korba, B. E. et al. (2000) Antiviral Res 44, 19-32; Korba, B. E. et al. (2000) Hepatology 31, 1165-75; Korba, B. E. et al. (2000) Antiviral Therapy 5, 95-105; Korba, B. E. et al. (2000) Antimicrob Agents Chemother 44, 1757-60). Like HBV, WHV can support HDV particle formation and infection, and the eastern woodchuck has been a useful model for HDV infection (Negro, F. et al. (1989) J Virol 63, 1612-8; Parana, R., Gerard, F., Lesbordes, J. L., Pichoud, C., Vitvitski, L., Lyra, L. G. & Trepo, C. (1995) J Hepatol 22, 468-73; Ciccaglione, A. R. et al. (1993) Arch Virol Suppl 8, 15-21; Bergmann, K. F. et al. (1989) J Immunol 143, 3714-21; Ponzetto, A. et al. (1984) Proc Natl Acad Sci USA 81, 2208-12; Ponzetto, A. et al. (1987) Prog Clin Biol Res 234, 37-46).
The dependence of HDV on its helper virus, HBV, could suggest that successful treatment of HDV infection would follow successful treatment of the supporting HBV infection. Unfortunately, this does not appear to be the case, as illustrated by recent results obtained with the drug lamivudine (Glaxo-Wellcome, Inc.) (Honkoop, P. et al. (1997) Hepatology 24 (Suppl), 1219 (Abstract); Lau, D. T. et al. (1999) Hepatology 30, 546-9). The lack of an effect of lamivudine on disease in HBV-HDV infected patients underscores the direct role of HDV in disease severity in such patients. Although lamivudine inhibits HBV and WHV replication, it does not affect the production of viral surface antigen (Lau, D. T. et al. (1999) Hepatology 30, 546-9; Doong, S. L. et al. (1991) Proc Natl Acad Sci USA 88, 8495-9; Korba et al. Hepatology, (2000) 31, 1165-75). The life cycle of HBV and other representatives of this family of viruses (for example, WHV) is unique in that the process of replicating genomic copies of the virus and the production of viral proteins (for example, HBV or WHV surface antigens) are differentially regulated (Ganem, D. 1996. Hepadnaviridae; In “Fields Virology” Fields B N, Knipe D M, Howley P, ed. Lippincott-Raven, Philadelphia, p. 2703-2737). Therefore, antiviral agents, such as synthetic nucleosides (for example, lamivudine) which target viral polymerases, may significantly inhibit HBV replication (for example, as measured by a reduction in viremia), but not affect the level of viral mRNA or viral protein production (for example, as measured by the levels of HBV surface antigen in plasma or serum). Given that the life cycle of HBV is unique in differentially regulating viral proteins and that HBsAg can be produced from a number of alternative transcripts, it has not been known to date what parameters are essential to achieving a therapeutic end point for HDV.
U.S. Pat. No. 5,747,044 discloses recombinantly produced immunogenic HDV polypeptides useful as vaccines.
U.S. Pat. No. 5,932,219 to Chiron discloses the entire genome of the hepatitis D virus, a family of cDNA replicas of the entire HDV genome, and teaches that portions of these cDNA sequences are useful as probes to diagnose the presence of virus in clinical samples. The patent also discloses proteins encoded by the cDNA that are useful in the production of vaccines. In particular, the '219 patent discloses a vaccine for hepatitis D which incorporates the p24 and p27 viral polypeptides. U.S. Pat. No. 5,750,350 to Chiron claims a kit useful in the analysis of hepatitis D virus which includes a peptide encoded by ORF 5 of the HDV genome. U.S. Pat. No. 5,747,044 claims a recombinantly produced immunogenic particle which raises antibodies against HDV, wherein the particle includes an immunogenic polypeptide encoded within ORF 5 of the HDV nucleotide sequence or its complement.
U.S. Pat. No. 6,020,167 assigned to Medeva Holdings B. V. discloses a method for treating chronic hepatitis, and in particular, hepatitis B, that includes administering a composition containing antiHBsAg.
U.S. Pat. No. 5,770,584 discloses a method for treating hepatitis virus infection by administering alkyl lipids or alkyl lipid derivatives.
U.S. Pat. No. 4,619,896 discloses a process for unmasking delta antigen in the blood of an animal, that includes treating serum with a surfactant and optionally with an antibody-antigen dissociating agent. The blood derived delta antigen is used as a diagnostic agent in the detection and determination of different classes of antibodies to hepatitis D virus.
United States statutory invention registration H1,345 discloses a method for preventing or treating hepatitis virus by administering a protein-prenyl transferase inhibitor.
Sureau, et al., Production of Infectious Hepatitis Delta Virus In Vitro and Neutralization with Antibodies Directed against Hepatitis B Virus Pre-S Antigens, Journal of Virology, February 1992, p 1241-1245 discloses that HDV particles produced in vitro are infectious and that (i) infectious particles are coated with HBV envelope proteins that contain the pre-S1 and pre-S2 regions, (ii) epitopes of the pre-S1 and pre-S2 domains of HBV envelope proteins are exposed at the surface of HDV particles, and (iii) that antibodies directed against those epitopes have neutralizing activity against HDV.
The nucleoside analog L-FMAU [2′-fluoro-5-methyl-β-L-arabinofuranosyl-uridine] is a known compound and has been shown to have significant antiviral activity against HBV replication in cell culture, and against the related duck hepatitis B virus in both cell culture and infected ducks (Aguesse-Gerrnon, S. et al. (1998) Antimicrob Agents Chemother 42, 369-76; Balakrishna Pai, S. et al. (1996) Antimicrob Agents Chemother 40, 380-6; Chu, C. K. et al. (1995) Antimicrob Agents Chemother 39, 979-81; Fu, L. et al. (1999) Biochem Pharmacol 57, 1351-9; Kotra, L. P. et al. (1997) J Med Chem 40, 3635-44; Kukhanova, M. et al. (1998) Biochem Pharmacol 55, 1181-7; Ma, T. et al. (1997) J Med Chem 40, 2750-4; Ma, T. et al. (1996) J Med Chem 39, 2835-43; Xu, A. S. et al. (1998) Biochem Pharmacol 55, 1611-9; Yao, G. Q. et al. (1996) Biochem Pharmacol 51, 941-7); Peek, S. et al. (2001) Hepatology 33, 254-66; Zhu, Y. et al. (2001) J. Virol 75, 311-22.
U.S. Pat. No. 5,587,362 and WO 95/20595 to Chu et al. disclose and claim L-FMAU and its pharmaceutical compositions for the treatment of HBV, and provides a detailed description of the synthesis of the compound. U.S. Pat. No. 5,567,688 to Chu et al. claims a method for the treatment of HBV using L-nucleosides including L-FMAU. U.S. Pat. No. 5,565,438 to Chu et al., claims a method to treat humans infected with Epstein-Barr virus (EBV) with L-FMAU. U.S. Pat. Nos. 5,808,040 and 5,753,789 disclose the use of L-FMAU to stabilize an oligonucleotide by including the compound at the 5′-terminus, 3′-terminus, or the interior of the oligonucleotide. WO 98/15375 discloses a method for the manufacture of L-FMAU.
L-FMAU has been shown to be a remarkably potent and fast-acting antiviral agent against WHV replication in chronically-infected woodchucks (Korba, B. et al. (1999) Antivir. Res. 41, A54; Chu, C. et al. (1998) in Therapies for viral hepatitis, eds. Schinazi, R. & Sommadossi, J. (International Medical Press, Atlanta), Vol. pp 303-12; Peek, S. F. et al. (1997) Hepatology 26, 425A(Abstract 1187); Peek, S. F. et al. (2001) Hepatology 33, 254-66; Zhu, Y. et al. (2001) J. Virol 75, 311-22. It has also been disclosed that L-FMAU induces suppression of WHV surface antigen in serum (Korba, B. et al. (1999) Antivir. Res. 41, A54; Chu, C. et al. (1998) in Therapies for viral hepatitis, eds. Schinazi, R. & Sommadossi, J. (International Medical Press, Atlanta), Vol. pp 303-12; Peek, S. B. et al. (1997) Hepatology 26, 425A and Peek, S. B. et al. (2000) Hepatology 33, 254-66. L-FMAU has been shown to have a favorable pharmacokinetic profile and sufficient oral bioavailability in rats and woodchucks that make it suitable for once daily administration (Wright, J. D. et al. (1995) Pharm Res 12, 1350-3; Wright, J. D. et al. (1996) Biopharm Drug Dispos 17, 197-207; Witcher, J. W. et al. (1997) Antimicrob Agents Chemother 41, 2184-7).
Because of the large number of persons infected with hepatitis delta virus, the devastating effects of hepatitis delta virus infection on the individual, and the lack of effective treatments, there is a critical need for new and effective methods and compositions for the treatment of hepatitis delta virus infection.
Therefore, it is an object of the present invention to provide methods and compositions for the treatment of a host, including a human, infected with hepatitis delta virus.
It is a further object of the present invention to provide a method for identifying compounds effective in the treatment of hepatitis delta virus infection.